Intermittent venous occlusion apparatus



Dec. 17, 1940.

S. A. KROLL INTERMITTENT VENOUS OCCLUSION APPARATUS Filed May 1 1937 4 Sheets-Sheet 1 PRESSURECOITRDL mu mm: PRESSURE mmcmns CUFF CONNECTIONS FIG. 1

3 I04 m2 [32 o 93 92 I I"; a I a f 1 a L5 0 l6 3 L- I30 F/G.2

STANLfY A. KROLL INVENTOR.

ATTORNEY.

Dec. 17, 1940. S,-A KRQL z,z2s,30s

INTERMITTENT VENOUS OCCLUSION APPARATUS Filed May 1, 1937 4 Sheets-Sheet 2 STANLEY ,4. KROLL INVENTOR.

m6 BY M %g- ATTORNEY.

Dec. 17, 1940. s. A. KROLL INTERMITTENT VENOUS OCCLUSION APPARATUS Filed May 1, 1957 4 Sheets-Sheet 5 FIG. 7

S TA NLE Y A. KROL L INVENTOR.

ATTORNEY.

Dec. 17, 1940. s. A. KROLL 8 INTERMITTENT VENOUS OCCLUSION APPARATUS Filed May 1, 1937 4 Sheets-Sheet 4 FIG. 9

STANLEY/4. KROLL INVENTOR BYMMA/%4%.

ATTORNEY.

Patented Dec. 17, 1940 UNITED STATES lNTERMlTTENT-VENOUS OCCLUSION APPARATUS Stanley A. Krcll, Queensvillage, N. Y., assignor toUJM. A. 1110., New York, N. Y, a corporation of-New York Application May 1, 1937, Serial'No 140,142

12 Claims.

My invention relates generally to an improved apparatus forincreasing collateral circulation in the.treatment.oiperipheral vascular disease, and more particularly the invention relates to an improved machine for automatically producing in- I termittent venous occlusion .in an extremity wherein there exists deficientcirculation.

One of themain objects of .my. present invention is to provide arr-automatically operating apm paratus forinflating .a .pneumaticcuii to a predetermined air pressure; a timing mechanism controlling the period of inflation of the cuff; and the apparatus further including a single devicewhich acts to predeterminethe maximum in- I -flation pressure of the cuii-toindicate the pressure in the vcuif,.-and to restorethe inflation pressure -to said maximum pressure whenever the cull pressure decreases during an inflation period.

Another importantobject of my invention is to provide in an automatically. operating cuff inflation apparatusof thetype =using-a timing mechanism to regulate the cuff inflation and deflation periods, a frequencyselector device for prei-setting the time durations ofthese periods: and a pressure-responsive means being. used for-simultaneously-keeping the' cuff inflated to a desired pressure during inflation periods and indicating the changes in pressure in the cuff during such inflation periods.

,Another important object of this invention is to provide a novel and .high-ly'improved pressureresponsive control mechanism for: a compressorvmotor unit, wherein the motor circuit is-dependcut for energization upon-the pre-setting 'of a motor circuit control element to-a position corresponding to a desired pressurepand a pressureactuated member beingemployedto actuate said controlelement to de-energize said motor circuit when the memberisadjusted to theabovementioned pressure position.

Yet another object of myinvention is to provide a highly flexible and reliable timing mecha- -nism for :an air compression apparatus; the mechanism-being. capable of energizingand deenergizing a-motor circuitin alternate periods, and a frequency selector device being associated with the timing mechanismto .provide a wide range of time .combinations for the aforesaid alternate periods.

An object of. my invention, in additionto those above, is the provision of anair compressionsystem for treating peripheral vascular disease, wherein the .system employs. an air reservoir. having numerous outlets to pneumatic .cuifs, and

or .auxiliaryair taps beingprovided for actuating. a

pressure control device, restoring the reservoir pressureto atmospheric after the expiration of predetermined periods of time and permitting entry of air under pressur when a motor-compressor unit is rendered operative.

And still another object of the invention may be stated to reside'in the provision of an alternate venous occlusion apparatus wherein the various units are compactly assembled in a cabinet Whose operating panel is provided with a pressureselector member adjustable to select and indicate any cuii inflation pressure of a range of suitable pressures; a frequency selector mechanism to select a desired one of a. range of inflation cycle combinations; a plurality of visual pressure indicatorsadapted to indicate the condition of the compressor unit at anytime; and pressure couplings. for one. or more pneumatic cuffs.

vStill. other objects may vbestated to residein the general improvement ofautomatic apparatus for treating peripheral vascular disease; 1 and more especially to provide an apparatus which is not only mechanically reliable, durable and. efficient .in operation, .butis characterized by its relative simplicity of assembly and manipulation.

.The novel features which I believe tobe characteristic .of my invention are setforth particularly in the appended claims;..the invention itself, howevenas tonbot-h its organization and mode of operation will best be understood by reference to the following 1 description taken in connection with the drawings in which I have indicated a constr-uction'whereby my invention may be carried into effect.

' In the "drawings:

Fig. 1 is a front View of the operating panel of a cabinet housing an apparatus embodying the invention,

Fig. 2 is a view of the apparatus when seen from the rear of the cabinet, V

Fig. 3 is a section taken along line 3--3 of Fig. 2, and loolringin the direction of the arrows,

Fig. 4 is a View takenalong section line 4-4 of Fig. 3, looking in the direction of the arrows,

Fig. 5 is a section ofan indicator detail taken on line 5-5 of Fig. 4, looking in the direction of the arrows,

Fig. 6 is asectional detail of the timingdisc,

Fig. '7 is a detailed view, partly sectioned, of the 50 combination pressure gaug and motor control switch,

Fig. ,8 is a sectiontaken along line 8-8-o-f Fig. '7, looking in the direction of the arrows,

Fig. 9 is a schematic representation of the 5? mechanical elements and electrical circuits of the present apparatus, and

Fig, 10 is a detailed View, partly sectioned, of the quadrant gear and associated pinion in Fig. '7.

Referring now to the accompanying drawings, wherein like reference characters in the different figures designate similar constructional elements, there is shown in Figs. 1 and 2' a cabinet I upon whose base 2 is securely affixed the intermittent venous occlusion apparatus chassis; the operating panel 3 is rigidly secured in position in one opening of the cabinet, while the rear opening (seen in Fig. 2) will be closed by a hinged panel. The panel 3 is preferably fabricated of an insulation material such as a phenol condensation product, hard rubber or the like. As shown in Fig. 1, the operating panel 3 is provided with the manipulating knob 4 of the frequency selector switch; the adjusting knob 84 of the air pressure control mechanism; the air pressure gauge 31; the viewing lenses 1 of the pressure indicator lamps; the pneumatic cuff couplings 3|; and the power control switch 9. Before explaining the constructional details of the various components of the apparatus, the schematic representation of Fig. 9 will be considered. The components comprise, in general, a motor I5 energized from a source of alternating current II, the motor being mechanically coupled to an air compressor I2.

The numeral II designates a source of alternating current which is used to energize the entire system shown in Fig. 9. The motor I0 is an alternating current operated motor, and is connected in circuit with source II in the following manner. One terminal of the motor is connected through lead 26 and lead 21 to one side of the source II. The other terminal of the motor is connected to the other side of source II through a path which includes lead 25, contact 24, armature 23, lead 2|, lead 20. contact I9, armature I8, lead I1, fuse I6 and nswi ch 8 The motor H) drives. by an suitable mechanical coupling, a centrifugal air compressor I2, the latter being mounted on a pair of soft rubber cushions I3 to eliminate vibrations. The air compressor has an air coupling to an equalizer I4, and the latter feeds an air reservoir I5 through a check valve 30.

The reservoir I5 is provided with six outlets. Three of these outlets are denoted by the numerals 3|, and they are adapted for connection to pneumatic cuffs. One of these cuffs is conventionally represented by the numeral 32, and the cuff is shown connected to a special coupling connector 33. The other three outlets are represented by the numerals 34, 35 and 36. Outlet 34 feeds a combined pressure indicating and motor control gauge 31. The outlet 35 is coupled to the equalizer I4 through the check valve 3!). The outlet 36 is a release outlet, and its function will be described at a later point. The check valve 36 is of a well-known and conventional construction, and is provided with inlet and outlet ports. The inlet port is coupled by the rubber tube 38' to the equalizer outlet, While the outlet port of the check valve is coupled by e 35' o the. port 35. Th air c nnec o between the inlet and outlet ports of the check valve is controlled by a rubber diaphragm 38, which is normally biased to prevent air connection between these ports. The numeral 38 denotes a spring pressed thimble which biases the diaphragm 38. The diaphragm 38 is normally seated, unless the air pressure from the equalizer I4 exceeds a predetermined setting of the spring of the check valve. The chief function of the check valve is to prevent reversal of air flow when the air pressure in the equalizer I4 is less than the air pressure in reservoir I5. In other words, as long as the motor I0 is operating to pump air into reservoir I5, then the check valve diaphragm 38 will be in open position. As soon as the motor In ceases operation, the diaphragm 38 closes the air connection to the equalizer.

Considering, now, the pressure release valve 36, it will be understood that it includes a conventional needle valve construction. The needle valve is normally unseated by the spring-ten sioned insulator bar 40. The spring 4I normally draws the bar 4|] in a direction to unseat the pressure release valve. The armature I 8 is drawn towards the relay coil 42, and it is to be understood that the relay coil 42 and armature I8 are schematically represented. The armature I 3 is fixedly pivoted at point 43, and when it is drawn towards the coil 42 the bar 40 is lifted upwardly with the result that the pressure release valve closes. There will now be described the electrical c rcuit which includes the relay coil 4?. that ntrols the pressure release valve. One terminal 44 of the relay coil may be traced to one side of the alternating current source I I through a path which includes lead 45, contact finger 46, metallic timer disc 41, the specific contact finger 48,

lead 49, terminal 50, the contact point 5| of the rotary frequency selector switch 52, the adjustable contactor 53, terminal 54, lead 55, fuse I 6, switch 9.

The opposite terminal 56 of the relay coil 42 may be traced to the source II through a path which includes lead 51, terminal 53 of the switch section of the pressure gauge 31, lead 59, the contact arm 66, the metallic pivot post 6I, lead 62, terminal 63, lead 64, lead 65 and lead 21. When the contactor I8 is drawn into contact with terminal I9, the following circuit is closed: From the metallic pivot 43 through lead I1, fuse I5 and switch 9 to one side of source I I, the terminal I9 being connected to the other side of source II through a path which includes lead 20, relay coil 10, lead 1I, terminal 12, lead 13, contact arm 14, metallic post 6|, lead 62, terminal 63, lead 64, lead 65 and lead 21.

The energization of coil 10 is accomplished, as explained above, by closing the switch I8I9. As soon as the coil 10 is energized, and it is to be understood that the coil 10 is part of a relay device which is other than the relay device described in connection with relay coil 42, the elec trical energizing circuit for motor II] is completed in. the following manner: The coil 10 draws the contact arm 23 into circuit-closing connection with terminal 24. The motor circuit may then be traced through a path which includes contactor 23, terminal 24, lead 25, through the terminals of the motor I0, lead 26, lead 21, through the source II, switch 9, fuse I6, lead I1, metallic pivot 43, contactor I8, contact I9, lead 20, lead 2I and metallic pivot 22. It will now be seen that to open the motor circuit the coil 42 must be deenergized thereby permitting switch I8-I9 to open, and thus, in turn, deenergizing coil 10. Opening of the circuit of motor Ill would result from the deenergization of coil 42, even though element failed to open contacts 23, 24. The result is that the switch 23-24 is automatically opened by virtue of the release of the element 80 which conventionally represents any well-known form of actuating mechanism for electro-magnetic relays. For example, the element 80 may opening of contactor be gravity-operated, or can be spring tensioned away from the coil 10.

At this point it will be realized that the motor circuit for the motor 15 may be opened in dependence upon the movement'of the selector disc 41, as well as upon the operation of the switch section of gauge 31. It has already been explained that energization of coil 42 depends upon the completion of a conductive circuit through the selector disc 41. It has, also, been explained that energization of coil results in circuitclosing movement of switch actuator 80. Since the switch 14, which is embodied in the pressure gauge 31, when opened causes the deenergization of coil 1c, thereby to break the motor circuit, it is essential to provide a so-called"locking circuit for positively preventing the motor circuit from being deenergized when contact finger 14 opens in response to a build-up of the air pressure in reservoir l5.

As will be explained in detail at a later point, the pressure gauge 31 comprises a switch section which includes the metallic pivot post 6 I to which are secured pivotally the contactors 60, 8| and 14. When the contactor 14 is in circuit-closing position, then the other two contactors BI and 50 are similarly in such closing positions. It is to be understood that the opening of these last named switches affects the energization of coil til only when the relay coil 42 is in energized state, i. e., during the active periods of timer disc 41. Assuming for the sake of illustration that it is desired to trip, or open, the motor circuit when the pressure in reservoir is equal to about mm, and the pressure gauge has been pre-adjusted to open the contactor 8| at 30 min. pressure, then the pressure gauge is constructed so that the contactor 14 is opened at a pressure of, for example, 2 mm. less than the predetermined maximum operating pressure. When the pressure responsive element 14' (schematically shown in Fig. 9) opens contactor 14, the coil 10 remains in energized condition, thereby not affecting the operation of motor [0. That 14 does not affect energize.- tion of coil 10 will be seen from the fact that the switch 8253 is in closed position forming a complete circuit through contactor 8|.

This by-pass, or shunting circuit, across switch 14 may be traced through the following path: contactor 82, contact 83, lead 84, terminal 85, lead 85, contactor 8!, metallic post 6|. When the pressure-responsive element opens switch 8i at the maximum pressure of 30 mm. the shunting circuit just described is opened, and this results in deenergization of coil 10. When the coil 10 is deenergized, the switch 2324, as well as switch 82.-33 is opened and the motor circuit thereby broken. Should the pressure in reservoir 15 begin to fall from the maximum value, still assuming that the coil 42 is energized, then the contactor 8! will be the first to swing into closed position but have no effect on the shunting circuit. This follows from the fact that theswitch 32fi3, which is in the shunting circuit, is still open; and, of course, switch 82-83 remains open as long as coil 10 is in deenergized state. Ourrent will not flow through the circuit including coil 10 until the switch 14 is closed by the pressure-responsive element which continues in its movement from switch 8! to switch 14 as the air pressure in reservoir l5 decreases toward 28 mm. As soon as switch 14 has closed, the circuit including coil 10 is energized; and the element 80 is actuated to close the motor-energizing switch 23-44 and the locking circuit switch ill-83.

Generally speaking, the pressure gauge 31 comprises a casing within which is disposed a disc 90 of insulating material upon which is mounted the post 6|, the disc 90 being mechanically coupled to the'large gear 9!. The gear 9! is driven by pinion 92 geared to the drive gear 93, and the latter being mechanically coupled to the manually adjustable knob 94. It is pointed out that the construction of the pressure gauge mechanism will be described in further detail at a later point, it being sufiicient for the present purpose to point out that the knob 94 may be actuated to adjust the angular position of post 51, and its associated contactors '14--8l-60, to a predetermined position with respect to the pointer 95. The latter is mounted on a shaft whose rotation is responsive to changes in air pressure in reservoir iii. The element 14 moves with the pointer $5 in response to the'pressure actuated shaft I12. The index. pointer 96 is pre-set, upon actuation of knob 94., to the maximum desired pressure indicated on the gauge dial 91.

In order to provide an emergency, or safety, switchv for the pressure control mechanism, the contactor 6D is provided at an angular spacing from contactor 8|, say for example 5 mm. of pressure, whereby the relay coil 42 may be automatically deenergized should the switch contactor 8| of gauge 31 open and the motor It still remain energized for some unknown reason. The safety switch circuit may be traced through a path which includes: contactor Bl], lead 59, terminal 58, lead 51, coil 42, lead 45, contact finger 4%, disc 41, finger 48, lead 49, contact 5!, contactor 53, lead 55, switch 9 to the source ll, and then through lead 55, lead 64, terminal 63 and lead 52 to metallic post 6|. When this safety circuit is open the relay coil 42- is deenergized, and, as a result, the bar 40 will be pulled into position to open pressure release valve 36.

An indicator light network is employed visually to indicate the various functions of the machine. For example, a green light IE0 is employed to indicate when there is no air under pressure in the cuff 32 thereby indicating that the pressure release valve is open, and the motor circuit is deenergized. The green-light I is connected to one side of source II through leads and 21; the opposite terminal of the light is connected to the opposite side of source H through a path which includes lead NH, switch l9'-l8 to lead [1, switch 9. As shown in Fig. 9, the green light is energized, because the coil 42 is deenergized, the motor circuit being open and cuff 32 being deflated.

A yellow light I02 is employed to denote the fact that the motor circuit is closed, and cuff 32 is being inflated. During this period, of course, the pressure in reservoir i5 is rising to its maximum value. One terminal of light N32 is connected to source II, by leads and 21, while the other terminal of the light is connected to the source ll through a path which includes lead I03, switch 24-43, lead 2|, lead 29, switch l9--lB, lead I1 and switch 9. It will be seen that with the yellow light energized, the green light Hill is off, and the motor circuit closed, the

cuff 32 being in the process of inflation since the pressure release valve is closed. The red light 104 indicates the fact that the motor circuit is open and the release valve 36 is closed, the pressure in reservoir l 5 having reached its maximum value. One terminal of the indicator 164 is connected to source II by leads 65 and 21, whereas the other terminal is connected through switch 24I23, leads 2I and 20, switch I9i8, and lead I? to source II.

There now will be described the general cons ructicn of the timing mechansim and its associated electrical circuits, attention being called to the fact that the constructional details of the timer mechanism are described at a later point. The timer comprises a metallic disc 41 which is mechanically coupled by a driving shaft I05 to a constant speed motor I06. Although the motor I66 may be designed to operate at any desired revolutions per unit of time, it is pointed out, by way of example, that the motor I05 operates at one revolution per hour, the motor being of any Well-known type used in present day alternating current mains-operated clocks. The motor I06 has its terminals electrically connected to the 60 cycle alternating current source II, and it will be seen that the switch 9 controls the energization of the motor I96, as well as the energization of the remaining circuits. The metal disc 41 is provided with a plurality of insulation segments HJ'I. It will be noted that there are provided two concentric circles of these segments, the outer circle including 15 equidistantly spaced segments of the same shape, and the inner circle comprising 10 segments equidistantly spaced from each other and spaced from the outer circle. It will be observed that the segments Itl' of the inner circle are of a configuration difierent from that of the segments IN.

A pair of opposed banks of contact fingers is associated with the circles of segments. One of these banks comprises four fingers 46, I63, I09, and III]. These fingers are spaced from each other, and are arranged in parallelism with the terminals thereof secured to an insulating block III. The opposing ends of these fingers are disposed in wiping, or contact, relation to the segments of the disc 47, as can be better seen in Fig. 9. It has already been explained that the finger 48 is constantly in contact with the metal face of the disc 41, and that the lead 45 connects the finger 45 to the terminal 44 of the relay coil 42. The fingers I09 and II t) are adapted to contact the inner circle I87, whereas the finger I08 contacts the outer circle of segments IEI'I. Each of fingers I08, Hi9, and II 0 is electrically connected to a contact stud in the frequency selector 52. Thus, finger I08 is connected by lead II2 to the stud 5|; the finger I09 is connected by lead II3, to a stud I I4. The finger H4 is connected by lead H5 to the stud H6.

The second bank of fingers, in general, duplicates the first bank in that it comprises four fingers 48', 48, 48" and Ill. The terminal ends of these parallel fingers are rigidly secured to insulating block II8, while the wiping ends of fingers 48' and 48 are adapted to be in sliding contact with the outer segments IIl'I. The free ends of finger 48" and II! are adapted to be in sliding contact with the inner segments Iiil'. It will be noted that each of the fingers of this bank is, also, electrically connected to a contact stud of the frequency selector 52, the finger 43' being connected by lead II9 to the contact stud I20. The finger 48 is connected by lead 49 to the stud 5|; the finger 43" is connected by lead 53' to the stud I2I, and the finger II! is connected by the lead I22 to the stud I23. It will be noted that the contact studs of the selector 52 are equidistantly spaced and arranged in a circle, the rotatable contactor 53 being constructed and arranged for sliding contact with the studs. Dotted lines have been shown to represent blank studs which are not electrically connected to any of the timer fingers. As previously explained the contactor 53 is connected by lead 55 to source II through switch 9.

In order to explain the operation of the timer mechanism let it be assumed, as shown in Fig. 9, that the contactor 53 of frequency selector 52 has been adjusted to contact studs 5I and I20, these studs being electrically connected to fingers 48 and 48 respectively. In this position of the selector contactor, the relay coil 42 will have an on-off cycle of two minutes; that is to say, the coil 42 will be energized for one minute and deenergized for one minute. This cycle is secured by arranging the segments III! at spacings from each other corresponding to one minute intervals. In other words, the spacings between the segments Hi1 represent intervals during which the coil 42 is energized for a period of one minute. Each segment I 01 occupies an angular distance which corresponds to three minutes of time interval. Hence, in one revolution of motor I06 contact fingers 48 and 48 will slide into and out of contact with each of the segments I07.

Since the finger 48 has a length which exceeds that of 48' by a distance equal to twice the spacing distance between successive segments I01, it will be seen that the coil 42 will only be energized for one minute periods, and deenergized for one minute periods. This follows from the fact that the electrical circuit through the contaotor 53 and coil 42 will only be closed when either of fingers 48 or 48 is in contact with a space between successive segments I91. It will be observed that in Fig. 9 the selector switch has been adjusted to studs 55 and I20 so as to select the on-off cycle determined by fingers 48 and 48'. In other words, a timer finger is electrically efiective when the selector contactor 53 has been adjusted to make contact with a stud corresponding to a particular timer finger.

By way of illustration, the segments I B? are shown as of a different timing pattern. Each segment It? has an angular distance equal to a five minute interval, and the spacing between segments are equal to a one minute interval. It is to be understood that spacing appearing in the body of each segment I01 represents a one minute time interval. Since the contactcr 53, as shown constructed in Fig. 9, can only contact three studs or less, it will be seen that many oombinations of on and off periods can be secured by proper selection of selector studs. The segments IM and I07 are not limited to the timing patterns disclosed herein, but they may assume various shapes which are desired for any desired timing conditions. Furthermore, the timer disc 4'! may be provided with additional insulation segment circles; and conversely, the timer disc may be simple and utilize only the outer circle of segments IIlI. Obviously, the number of fingers used for the timer disc will depend in length and number upon the timing cycles desired, and the construction of the frequency selector 5.! may be employed to lessen or increase the number of combinations in the timing cycle. Again, the motor I 05 can be varied in speed, it it is desired to introduce another range of timing possibilities. The motor I46 need not be an electrically energized motor, but, in general, it can be any constant speed device capable of driving disc 47.

There will now be explained the mechanical construction details, as well as the relative positions, of the elements which are schematically shown in Fig. 9. It has previously been explained that Fig. 1 shows the appearance of the operating panel of the apparatus; the frequency selector device 52 being shown labelled Frequency, and the numeral 4 denoting the manipulating knob which adjusts the position of contactor 53 of Fig. 9. It will be seen that any desired combination of on-off cycles may be selected by rotating the knob, and in Fig. 1 it has been shown that a cycle of one minute on and three minutes off has been selected. To make this change from the position shown in Fig. 9, it is only necessary to adjust contactor 53 to contact solely with stud 5|, thereby selecting finger I08.

The pressure control knob 94 on the operating panel in Fig. 1 is shown arranged to pro-set the position of index 95 of the pressure gauge 31, and it will be observed in Fig. 1 that both this index and the pointer 95 are movable across the face of dial 91. The mechanical details of the pressure gauge 51 are shown in fuller detail in Figs. 7 and 8, and will be described at a later point. Referring now to Figs. 2, 3 and 4, it ill be seen that the motor 50, compressor It and equalizer 54 are mounted on a chassis pan I30. The equalizer I4, as seen in Fig. 2, is rigidly secured to the pan by brackets 53!, the ooupiing I32 providing the air connection between compressor I2 and the equalizer. While the compressor I2 is shown coupled to the motor I by a belt drive I2, it is to be clearly understood that any other type of mechanical coupling may be employed such as gears, chain drive or flexible coupling.

2 additionally shows the gears 93 and 02 which mechanically couple the-knob 234 to the gear M of the pressure gauge. Reference is made to Fig. 3 and 4 which show more particularly this gear relation, as well as the position of the pressure gauge casing on the rear face of the operating panel. Within the interior of the pan I30 are mounted the reservoir I5, the on-off switch ii, the fuse I5, frequency selector 52, the timer disc 41 and its associated fingers, motor Hi5, rubber cushions I3, and the wiring cables denoted generally by the numeral I52. On the exposed face of the pan I30 are mounted, in addition to the motor, compressor and equalizer, the relays 42' and 10'. It will be understood that the numeral 42 denotes the assembly of elements which includes relay coil 42 and its associated switches. As shown by the dotted rectangle in Fig. 3, these elements are ail normally housed within a shield can, and Fig. Zshows theappearance of the shieid can. 'It will be observed that the relays 15 and 42 are arranged atone side of the pan with the relay 10 to the rear. Fig. 2 further shows the air connection between the reservoir I5 and the equalizer I4, the check valve 30 being disposed in the rubber coupling connection to the air tap 35. The air connection between reservoir I5 and the pressure gauge 31 is shown in Fig. 2, and it will be understood that this connection comprises a rubber coupling 31' between the pressure gauge 31 and the air tap 34.

In order effectively to eliminate-vibration and noise due to the operation of the motor and compressor, they are mounted on rubber cushions I3. The cushions are each secured at the ends thereof to the undersurface of pan I30, and in Fig. 3 are shown the bolts I3 which rigidly fix the ends of the cushions to the pan. The motor I0 and compressor I2 are both rigidly securedto a plate I0, shown as a dotted rectangle in Fig. 3, and the plate is bolted at its four corners to the pair of cushions I3. Fig. 3 shows the bolts I5 which rigidly afiix the bedplate I0 to the rubber cushions. In this way there is a so-called floating power suspension provided for the motorcompressor unit. It will be observed from Fig. 3 that the equalizer I4 is positioned between relay and the motor compressor unit. Further, the synchronous motor I05 is positioned to the rear of a specialcompartment I30, and within this compartment are housed the timer disc 41 and the contact fingers thereof. As shown in Fig. 3, the contact fingers are aifixedto block H3. It will be understood that the second block I I I, and its associated contact fingers, will be mounted within the compartment I30; the compartment is bolted to the pan I30.

In Fig. 4, there is shown the manner of positioningthe indicator lights I00. I02 and I04 on the rear face of panel'3. A detail of the indicator light I04 is shown in Fig. 5, and it will be seen that the light I04, or bulb, is secured to the rear face of panel 3 by a bracket I04. There is provided aconventional socket for the bulb, the electrical leads I40 to the socket being spaced by insulation washers. The bracket end is gripped between the washers; the other end of the bracket I04 is gripped between the rear face of panel 3 and a threaded nut I49. The latter is threaded to a tube I4I which is affixed to a bore in panel 3 by an outer thread. The glass bezel, or glass lens. 1 is fitted across the outer opening of tube MI by any well known form of securing device 1. The lens 1 may be colored red; or the bulb I04 may, if desired, have a red coating and the element 1 be colorless. It will be understood that the remaining indicators E62 and I00 are similarly constructed; in each case the bulbs may be coated with the specific color desired, or the viewing lenses may be colored.

A detail View of the timer disc is shown in Fig. 6; and it will be observed that the disc 41 has been sectioned to show the manner in which the outer segments I81 and the inner segments I01 are provided. The disc is preferably made of copper,.and is produced with spaced depressed, or shallow, areas corresponding to segments. These shallow areas are filled with shellac, or some other thermoplastic insulation material capable of hardening at room temperature. In this way the spaced circles of segments I01 and I01 are provided. The disc 41 may be electroplated on a patterned mold, such a method of producing a disc with spaced, shallow areas being well known to those skilled in the art. Of course, the copper disc 41 will be of relatively thin plate,

and the shallow areas thereof will be given such shapes as is desired. The shellac is poured over the face of disc 41 to fill the shallow depressions thereof; after solidification the excess shellac is scraped, or rubbed, from the disc face by any desired abrasion method. The shellac segments will finally appear as shown in Fig. 9.

The disc 41 is shown rigidly coupled to synchronous motor shaft I05; the disc is secured by rivets I42 to a hub I43. The latter is rigidly affixed to the shaft I05, insulation washers I43 spacing the disc and rivets from shaft I05. In Fig. 3 is shown the disc 41 with its rigid insulation coupling to motor I06.

There will now be described the structural details of the pressure gauge 31, special attention being directed to Figs. 7 and 8 showing longitudinal and transverse sections of the gauge. The gauge comprises, in general, apressure-responsive indicator section, and a pressure-actuated motor circuit control section. The gauge comprises a pair of cylindrical casing sections which are secured, as by set screws, to provide a casing 31" having a solid base I59; the latter has a central bore into which is threadedly fitted the air inlet port II. The forward casing section may be composed of a phenol condensation product, and the rear casing section of metal; or both sections may be of metal. As shown in Fig. 9, the air connection 31 is made from air tap 34 to this port I5I. The open end of casing 31 is closed by the circular window I52 through which is viewed the pressure dial 91. The window I52 may be made of glass, Cellophane plate or any other transparent material. The dial 91, bearing pressure indicia as shown in Fig. 1, is spaced from the window I52 to accommodate the pressure actuated pointer 95 and the pre-set index 96. The casing 31" is provided with spaced, peripheral, bored bosses I53 to permit the casing to-be secured to panel 3 in the position shown in Figs. 1 and 3.

The dial 91 is rigidly affixed to a pair of spaced metal posts I54, and these posts are rigidly afiixed in turn to the rear casing section. For example, the posts I54 may be threaded to the base I50 of the casing. The pointer 95 is actuated by changes in pressure within the aneroid shell, or bellows, I55. This shell is of a conventional and well known construction, and comprises a pair of opposed metallic plates, which are very thin, and each plate being corrugated. The plates are sealed at their periphery, as is well known to those skilled in the art. This expansible diaphragm I55 will swell-upon admission of air under pressure. The rear plate I55 of the diaphragm is rigidly affixed to the foundation block I56, and the latter is in turn, secured to the spacer I51. It will be understood that the port I5I has an air connection to the interior of bellows I55, a narrow bore being provided from the port I5I through the various members between the plate I55 and the port.

The forward plate I58 of the aneroid bellows is mechanically coupled to a link connection shaft I59 which has provided on it a pinion I60. The pinion is geared to quadrant gear I6I, and the latter is pivoted between pair of supporting plates I62 and I63. These support plates are maintained in spaced relation by posts I64. The quadrant I6I is actuated by a pin I 65, the pin being rigidly secured to the rod I66. This last named rod is mounted between blocks I64, both of which blocks are secured to the rear face of plate I63. It is to be noted that the plate I63 is broken away in Fig. '7 to show the relation between the quadrant I6I, rod I66 and pin I65.

The ends of rod I66 are pivotally secured to blocks I64 by substantially frictionless bearings; and these bearings are shown as conventional conical bearings. The rod I66 is rotated about its bearings by means of a coupling to plate I59, the coupling comprising a yoke member I1| rigidly secured to plate I 58, and the yoke being in contact with a pin I projecting from the rod I66. As shown in Fig. '1, the pin I10 projects away from the plane of the paper, and is to be understood to be in contact with the forward portion of the yoke I1I. In this way, when the air pressure expands diaphragm I55, the yoke I1I pushes against pin I10 thereby rotating rod I66. This, in turn, swings pin I 65 through an arc, and causes motion of the quadrant |6|, about its pivots. The angular motion of the quadrant |6| is converted into rotational motion of pinion shaft I 59. The pinion shaft I59 is supported between plates I62 and I 63, a spring I1 I normally maintaining the shaft in its zero pressure position. The coil of the spring is shown positioned about the shaft adjacent its bearing on plate I63, and the outer end of the spring being secured to post I64. This is shown more clearly in Fig. 10.

The pointer 95 is rigidly secured to the pinion shaft I59 by means of an extension shaft I12, the extension shaft having a hub section I13 which is provided with a bore receiving the tapered end of pinion shaft I59. The tapered end of the pinion shaft is frictionally fitted into the hub section I13 so that the pointer 95, ex tension shaft I12 and pinion shaft I59 move as a single unit. Hence as the bellows I55 expand, this expansion is translated into a rotary pressure indication of pointer 95; the spring I1I' normally biasing the pointer 95 to the zero reading on dial 91. Of course when the chamber I55 is deflated, the spring I1I restores the pointer to its zero position.

It is pointed out that the construction of the pressure gauge up to this point is of a well known form, and is, in general, of a type well known in low air pressure indicating instruments, such as employed in barometers, air speed indicators, etc. The rotational movement of the shaft I12 is utilized to perform an additional function; this function is the control of the motor energizing circuits in response to air pressure variations. In Fig. 9, the pressure gauge has been shown as including three switches comprising contactors 60, BI, and 1.4. In Fig. 1, these contactors are shown as independent pointers, or pins, mounted for rotation about a metallic post 6|. The post 6| is riveted to an insulating disc 90. This disc 90 is screwed to a metal collar 90' and the gear 9|. The gear 9|, collar 90 and disc 90 are securely fitted, as one unit, to a support tube I80. A shoulder on the forward end of the tube bears against the exposed face of dial 91, and a spring washer I8l disposed between the forward face of gear 9| and the rear face of dial 91, positively maintains the gear unit properly centered on support tube I80. The index 96 is rigidly affixed to the shoulder of the support tube I80 so that rotation of gear 9! results in movement in unison of index 96, the support tube I80, washer |8| and the disc 90.

A slot 9| is provided in the periphery of casing 31' in alignment with gear 9|, the slot 9| being adapted to receive the intermediate gear 92, shown in Fig. 9, which is driven by rotary adjustment of knob 94. It will, therefore, be seen that adjustment of knob 94 varies the position of index 96 with respect to the indicia on dial 91 so as to indicate the maximum operating air pressure desired. Simultaneously the adjustment of knob 94 pre-sets the position of post 6|, and its associated contactors, to a predetermined angular position with respect to the dial index 06.

The contactors are disposed in axial alignment between a shoulder at the free end of post 6| and the disc 90. Each contactor is provided with a hub; and each hub is disposed within the center of a spring coil, as more clearly shown as in Fig. 8. In this last figure, it will be seen that the contactor 60 has its hub secured to one end of spring 60', the other end being rigidly secured to a post 6|. The post 6| is rigidly affixed to the disc 90 so as to move therewith, and it will be understood that the spring associated with each contactor has one end thereof rigidly affixed to post GI.

Each coil spring biases its respective contactor into contact with itsrespective' connection post. Thus, the contactor E is -normally spring biased into electrical contact withpost 200'; contactor 8| is spring biased into electrical contact with" post EDI; and contactor 14 is normally biased intoelectrical contact with post 292. These posts 2M), 201, 202 are spaced from each other, and each of them is rigidly afiixed to the insulation disc 9i). It will be noted that these contact postsare riveted to the insulation disc in the same'manner as post 61. Of course, the electrical connections to these contact posts will .be readily understood from Fig. 9, which shows the connections between the gauge binding posts and thecontact posts associated with each respective contactor pivotally mounted on post 6|.

Referring again to Fig. 9; it will be observed that the member 14' has been described as being adjustable in synchronism with pointer 95 in responseto increase, or decrease; inair pressure. In Fig. 7 is'will be seen that the member 14' physically comprises a trip arm, or vane, one end of which is rigidly secured to the hub section [130i extension shaft I12; and any well known form of afllXiIlg device may be used for this purpose. The free end of the'van'e is bent at right angles, and is provided with a coating of insulating material 14". It will be noted, furthermore, that the bent section 14" of the vane has a length such that it is capable of tripping contactors 14, BI and B0 in succession. Additionally, the section 14" is in alignment with the pointer 95, and such alignment perisists' throughout rotational movement of shaft I12. As shown in Fig. 1,.expansion of diaphragm 155' results in rotation of tripper member 14' away from the plane of the paper until section 14 contacts contactor 14. Further movement of the vane causes contactor 14 to move in unison therewith, and still'further rotation of' the vane results in moving contactors BI and 621 out of electrical connection with their respective contact posts.

A special stop post set may be provided on disc 90 so that when the vane 14 has opened the contactor 63- it cannot be moved beyond stop 3%. As explained in connection with Fig. 9, the contactor 8! is designed to open the motor circuit at an air pressure corresponding to the maximum operating air pressure. Therefore, in actual practice the index 9i} will be set in alignment with contactor 8! so that the index will actually indicate the pressure at whichthe motor circuit will open at maximum pressure. Of course, Fig. 9 being schematic, the index BB'has not been shown in alignment with contactor 8!, this having been omitted to permit a clear showing of the electrical relations between the contactors and the circuits thereof. As the vane member 14' rotates back to its zero, or normal, position, the contactors 69, 8| and 14 swing back into electrical contact with their respective contact posts. Each contactor has been shown provided with a counterweight 31H to provide symmetry of design and balance. The contactor 14 will be opened when the air pressure increases to a point 2 mm., less than the maximum pressure, whereas the contactor 60 opens when the maximum operating pressure has been exceeded and the motor circuit fail to open.

It will now be appreciated that the pressure gauge is a combined indicating and motor circuit control mechanism. Adjustment of knob 94 presets the motor circuit control switches to a predetermined angular position vvith respect to pointer 95 and vane member 14', the index 95 showing this position as a maximum operating pressure. Increase of air pressure in reservoir I is translated, through the agency of diaphragm I55 and the coupling to shaft I12; as a pressure indication shown by pointer 95 and at the same time as arotational movement of the vane member 14'. Hence, the motor-compressor unit l0l2 is not only regulated by the movement of the timer disc 21, but itis, also, under the control of the pressure responsive mechanism embodied in gauge 31. Additionally, it will be observed that the pressure releasevalve 36 is only actuatedto deflate the cuii'32 when the timer'disc 41 deene'rgizes relay coil 42, Of course, the relay coil 52 is also'deenergized when the emergency contactor iii? is opened. It is not believed-necessary toexplain the various electrical conductors and wiring shown in Figs. 3, 4, '1 and 8, because these have been explained in detail in Fig. 9.

While Ihave indicated and described a system for carrying my invention into effect, it will be apparent to one skilled in the art. that my invention is by no means limited to the particular organization shown and described, but that many modifications may be made without departing from the scope ofmy invention, as set forth in the appended claims.

What I claim is:

1. In combination, an air reservoir provided with at least one air coupling for connectionto a pneumatic cuff, said reservoir being provided with an air inlet port and a normally open pres sure release valve, a relay adapted to close said valve when energized, an energizing circuit connected to said relay for energizing the latter, a motor-compressor unit, said compressor having an air coupling to said inlet port, a'control switch connecting said motor tosaid energizing circuit, said relay being adapted to actuate said control switch upon energization of the relay, 2. second control switch controlling the energization of said relay, said second control switch including an element constructed andarranged to open and close the circuit through the relay in a predetermined cyclic manner.

2. In an apparatus as defined in claim 1, a third control switch controlling the energization of said motor, and means responsive to an increase in air pressure in the reservoir to a desired pressure for opening the third switch.

3. In an apparatus as defined in claim 1, said element comprising a metallic plate provided with a predetermined pattern of insulation areas, and a constant speed device being coupled to the plate to drive the latter.

4. In a system as defined in claim 1, said last element comprising a constant speed operatedmetallic plate provided with a pattern of spaced insulation segments, said second switch comprising a plurality of pairs of contact fingers in contact with said plate, and a frequency selector switch connected to said fingers to select a desired pan.

5. In a system as defined in claim 1, said reservoir being provided with an auxiliary air outlet, and a pressure responsive indicator having an air coupling to said auxiliary outlet.

6. In a venous occlusion apparatus, a cabinet adapted to house a motor-compressor unit, an air reservoir operatively associated with said unit, relays to control the motor circuit and timing mechanism for the motor circuit, an operating panel, means on the panel to pre-set a maximum desired press ure, said means including a device which is automatically responsive to the air pressure within said reservoir, a frequency selector switch, and a plurality of air outlet devices connected to the reservoir.

'7. In combination, in an intermittent venous occlusion apparatus, a cabinet provided with an operating panel, a motor-compressor unit disposed within the cabinet, an air storage chamber having an air coupling to said unit, at least one air outlet means associated with said chamber, means within the cabinet for automatically controlling the operation of said unit in a predetermined cyclic manner, means on the said panel to pro-set a maximum desired air pressure With in said chamber, said last means including a rotatable switch-tripping element having an air coupling to said chamber, and a plurality of control switches in circuit with the motor of said unit, said switches being arranged in succession in the path of said rotatable element, and a single member for adjusting the position of said control switches with respect to said rotatable element.

8. In combination, in an intermittent venous occlusion apparatus, a cabinet provided with an operating panel, a motor-compressor unit dis posed within the cabinet, an air storage chamber having an air coupling to said unit, at least one air outlet means associated with said chamber, means within the cabinet for automatically controlling the operation of said unit in a predetermined cyclic manner, means on the said panel to pre-set a maximum desired air pressure within said chamber, said last means including a device for automatically controlling the operation of said unit in response to a predetermined increase of the pressure'in said chamber, said last named device comprising a control switch connected in the motor energizing circuit, and an air pressure-responsive element having an air coupling to said chamber means supporting said element for rotation in a path including said control switch, and means for adjusting the position of said control switch with respect to said element whereby said element is adapted to open said control switch at various pressures in said chamber.

9. In combination, an air reservoir provided with at least one air coupling for connection to a pneumatic cufi, said reservoir being provided with an air inlet port and a normally open pressure release valve, a relay adapted to close said valve when energized, an energizing circuit connected to said relay for energizing the latter, a motor-compressor unit, said compressor having an air coupling to said inlet port, a second energizing circuit, provided with a control switch,

adapted to be connected to said motor to energize the latter, and said relay having an armature adapted to actuate said control switch upon energization of the relay, and means for controlling the energization of said relay in a predetermined cyclic manner.

10. In combination, an air reservoir provided with at least one air coupling for connection to a pneumatic cuii, said reservoir being provided with an air inlet port and a normally open pressure release valve, a relay adapted to close said valve When energized, an energizing circuit connected to said relay for energizing the latter, a motor-compressor unit, said compressor having an air coupling to said inlet port, a second energizing circuit, provided with a control switch, adapted to be connected to said motor to energize the latter, and said relay having an armature adapted to actuate said control switch upon energization of the relay, means for controlling the energization of said relay in a predetermined cyclic manner, a second control switch controlling the energization of the motor, and means responsive to a desired increase of air pressure in the reservoir for actuating said second control switch.

11. In combination, an air reservoir provided with at least one air coupling for connection to a pneumatic cuii, said reservoir being provided with an air inlet port and a normally open pressure release valve, a relay adapted to close said valve when energized, an energizing circuit connected to said relay for energizing the latter, a motor-compressor unit, said compressor having an air coupling to said inlet port, a second energizing circuit, provided with a control switch, adapted to be connected to said motor to energize the latter, and said relay having an armature adapted to actuate said control switch upon energization of the relay, and means for controlling the energization of said relay in a predetermined cyclic manner, said last controlling means including a frequency selector mechanism.

12. In an intermittent venous occlusion-apparatus of the type employinga motor-compressor unit and an inflatable cuff air-coupled to the compressor, a timing mechanism to regulate the cuff inflation and deflation periods, a frequency selector device for pre-setting the time duration r of sa1d periods, and means, responsive to the air pressure produced by said compressor, for simultaneously maintaining the cufi inflated to a desired pressure during inflation periods and indicating the changes in pressure in the cuff during such inflation periods.

STANLEY A. KROLL. 

